In a built-in stapler built into a machine including a driver unit (2) for ejecting staples against sheets of paper to be bound by means of a motor-driven driver; and a clincher unit (3) for folding legs of the staples, the driver unit and the clincher unit being held independently from each other with a determined distance therebetween so as to move respectively, stopping positions at one ends of respective moving ranges of the units (2, 3) are set to be displaced from each other, and the stopping position of the clincher unit (3) is provided at an inner side in the moving range than the stopping position of the driver unit (2). <IMAGE>